This may just be a the way that I see it, and possibly not actual fact, but I feel that the the closer the cb is to the object ball, the ob is more subject to having it's path altered with throw or 'clinging' caused by unintended spin on the cb. However, this effect is greater with thicker cuts than with thinner cuts, so it may not be your problem. Maybe just the way I see it, but when the cb is close (10cm or more), I tend to either cut thinner than the way I see it, and/or use enough outside english to cover for what I see as cling/throw. As another poster mentioned, it also helps to look down onto the balls from a little bit higher head position than you normally might use during other shots.
dave